\title{Resolutions over symmetric algebras with radical cube zero} \author{David J. Benson} \address{Department of Mathematics, University of Aberdeen, Aberdeen AB24 3UE} \begin{abstract} Let $\Lambda$ be a finite dimensional indecomposable symmetric algebra over an algebraically closed field $k$, satisfying $J^3(\Lambda)=0$. Let $S_1,\dots,S_r$ be representatives of the isomorphism classes of simple $\Lambda$-modules, and let $E$ be the $r\times r$ matrix whose $(i,j)$ entry is $\dim_k \Ext^1_\Lambda(S_i,S_j)$. If there exists an eigenvalue $\lambda$ of $E$ satisfying $|\lambda|>2$ then the minimal resolution of each non-projective finitely generated $\Lambda$-module has exponential growth, with radius of convergence $\frac{1}{2}(\lambda - \sqrt{\lambda^2 - 4})$. On the other hand, if all eigenvalues $\lambda$ of $E$ satisfy $|\lambda|\leq 2$ then the dimensions of the modules in the minimal projective resolution of each finitely generated $\Lambda$-module are either bounded or grow linearly. In this case, we classify the possibilities for the matrix $E$. The proof is an application of the Perron--Frobenius theorem. \end{abstract}